The objective of this investigation is to increase our understanding of the pathogenic mechanisms of Pseudomonas aeruginosa in chronic respiratory infections of cystic fibrosis (CF) patients. P. aeruginosa produces a variety of extracellular products which may play a significant role in the pathogenesis of Pseudomonas infections depending upon the site of infection. The ability of P. aeruginosa to maintain chronic respiratory infections in cystic fibrosis patients is associated with the organisms' ability to convert to an alginate-secreting form. Alginate is an exopolysaccharide, and its production gives P. aeruginosa a muciod phenotype. This project proposes to elucidate the genetic control mechamisms of alginate biosynthesis in a mucoid Pseudomonas strain isolated from a cystic fibrosis patient. Employing recombinant DNA technology, the role of chromosomal genes active in the regulation of alginate synthesis will be investigated. Analysis of DNA restriction fragments which contain alginate (alg) control genes will extend our understanding of the expression of this P. aeruginosa virulence determinant. In addition, this study will work towards the elucidation of the genes and gene-products which are directly involved in alginate bioslynthesis. Characteristics associated with alginate (alg) mutations will be determined, and detailed mapping of alg markers will be performed. The isolation of alg+ genes by gene cloning in Pseudomonas will be attempted to directly determine the organization of alg+ genes and their functions.